1. Field of the Invention
The present invention relates to a cooling apparatus using boiling and condensing refrigerant for cooling a heat generating unit such as a semiconductor device or the like.
2. Description of Related Art
In a conventional cooling apparatus using boiling and condensing refrigerant, the refrigerant filled in the refrigerant tank is boiled by absorbing heat. Then, the boiled and vaporized refrigerant is condensed and liquefied in the radiator, and heat is repeatedly absorbed by the liquefied refrigerant. Accordingly, in order to absorb the heat in the refrigerant tank efficiently, it is necessary for the flow of the vaporized refrigerant inside the radiator to be a circulating flow (uniform flow).
In the cooling apparatus using boiling and condensing refrigerant, as disclosed in JP-A-3-283454, JP-U-62-162847, or JP-A-51-118038, there is provided a tube for forming a passage (hereinafter referred to condensed liquid passage) to return the refrigerant from the radiator to the refrigerant tank and such tube is soaked in the refrigerant tank.
In such a cooling apparatus using boiling and condensing refrigerant, since the condensed liquid passage is soaked in the refrigerant within the refrigerant tank, the condensed refrigerant liquefied and falling may be heated before reaching an outlet of the condensed liquid passage. As a result, it is hard for the refrigerant to fall in the condensed liquid passage and to reach the outlet of the condensed liquid passage efficiently. Accordingly, the refrigerant does not circulate efficiently, and the radiating ability may be deteriorated.
As a conventional cooling apparatus using boiling and condensing refrigerant in which the circulating flow is formed, as disclosed in JP-A-51-39442, or JP-U-58-135954, the condensed liquid passage is disposed outside the refrigerant tank and connected to the radiator below the refrigerant tank.
However, in the cooling apparatus using boiling and condensing refrigerant as disclosed in JP-A-51-39442, or JP-U58-135954, since the condensed liquid passage is formed as an outside piping, the manufacturing cost may be increased and the reliability of the connecting portion between the refrigerant tank and the liquid may be deteriorated.
Further, in the cooling apparatus using boiling and condensing refrigerant as disclosed in JP-A-51-39442, or JP-U58-135954, since two pipes for connecting between the refrigerant tank and the radiator are needed, the number of the parts as well as the manufacturing cost may be increased and the apparatus may be large sized.